1. Field of the Invention
This invention relates to a novel class of bovine-murine hybridomas which produce neutralizing monoclonal antibodies to bovine herpesvirus-1 (BHV-1). BHV-1 is the agent responsible for infectious pustular vulvovaginitis and bovine rhinotracheitis. Secondary infections associated with rhinotracheitis may develop into an economically devastating disease known as "shipping fever." Efforts to control diseases induced by BHV-1 have been hindered for want of reliable diagnostic reagents and effective therapeutic agents.
2. Description of the Prior Art
Attenuated vaccines which have been developed against BHV-1 are typically characterized by undesirable side effects, and the killed vaccines are largely ineffective. Lupton et al. [Am. J. Vet. Res. 41: 383 (1980)] have reported on a crude subunit vaccine for protecting calves against the infection and shed of infectious BHV-1. Van Drunen et al. [J. Virol. 59: 401 (1980)] and Babiuk et al. [Virology 159: 57 (1987)] have shown that the administration of each of three major envelope glycoproteins of BHV-1 to calves will protect against combined challenge with BHV-1 and Pasteurella haemolytica, but not against viral replication and shedding. Passively administered, murine, monoclonal antibodies specific for epitopes on the three envelope glycoproteins were found by Marshall et al. to be nonprotective against BHV-1 infection in calves.
Presumably, monoclonal antibody of bovine origin would have advantages in many applications, including: the determination of key epitopes responded to by the host; cooperation between antibody and host accessory immunologic cells; repeated prophylactic or therapeutic administration of antibodies to the host; production of some types of anti-idiotypic antibodies; and as control reagents for serologic assays. For example, Srikumaran et al. [Abstract of Papers, 67th Annual Meeting of the Conference of Research Workers in Animal Disease, 86: Abstr. No. 143 (1986)] fused lymph cells from a calf immunized against infectious bovine rhinotracheitis virus (IBRV) with the nonsecreting cell line SP2/0. Two of the recovered hybridomas secreted nonneutralizing, bovine monoclonal antibodies that reacted with IBRV in both indirect solid-phase radioimmunodiffusion assay (RIA), and indirect fluorescent antibody assay (IFA). Tucker et al. [Hybridoma 3(2): 171 (1984)] demonstrated that antibody secretion vigor of interspecies hybridomas could be enhanced by re-fusing a chemically selected mouse/calf hybridoma with immunized calf lymph node cells. In contrast to the original mouse/calf fusion products which failed to maintain antibody secretion in culture, the re-fused lines carried two to three times the number of bovine chromosomes as the single-fused hybridoma and maintained active antibody secretion over a 5-month period.